"Costco could pay another $100,000 dollars to a lab to process and test, and then be able to put ACEA A5 on it."
Not if they want it also to be Dexos compliant. The specs are mutually exclusive concerning their shear viscosity.
ACEA A5/B5 oils are Upper Mainline lubricants. They are designed for use in high performance gasoline and light duty diesel engines that are specifically designed to use a low viscosity oil. These oils may be unsuitable for use in some engines.
360.lubrizol.com
360.lubrizol.com
You are misinformed, and are also spreading disinformation in stating that The Costco Oil which meets Dexos specification is also ACEA A5 compliant or could be ACEA A5 compliant if tested to it. The manufacturer of the Costco oil is readily available on the internet, you can give them a call to confirm.
I re-read the manual too, page 9, "If the ACEA A5 engine oil is not available in your country, you are able to use API SM & ILSAC GF-4 (or above) or ACEA A3." Is that why you think you are able to use the the Costco oil? You do know ACEA A5 is available in the USA right?